Stair climbing apparatus

ABSTRACT

The stair-climbing apparatus has a series of articulating wheel sets extending below the platform. All of the wheel sets are vertically adjustable to negotiate stairways and similar changes of elevation. The lead wheel set is fixed longitudinally relative to the platform, while following wheel sets are longitudinally adjustable to adjust for the pitch or slope of different stairways. The apparatus uses sensors (e.g., mechanical, infrared, ultrasonic, etc.) to detect the presence of the stair risers and their height, control of the assembly being accomplished by a control circuit on board the machine. The wheel sets are raised and lowered independently of one another by pantograph mechanisms extending between the platform and the wheel sets. The horizontally adjustable wheel sets are positioned by a longitudinally disposed rack on the platform.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to powered devices for ascendingand descending elevations, and particularly to a stair-climbingapparatus capable of free operation (i.e., not secured to anotherstructure) on a flight of stairs or the like.

2. Description of the Related Art

The need for powered mechanical assistance for persons that haveoccasion to ascend or descend elevations has been known for aconsiderable period of time. This is particularly true for the elderlyor infirm who have need to travel between floors of a multiple storybuilding. The need also arises when transporting large and/or heavyarticles between floors in a multiple story building, e.g., large officemachines, such as console copiers, office or other furniture, etc.

Accordingly, elevators were developed well over one hundred years ago,and escalators were developed somewhat later. However, elevators andescalators require that the building structure provide for such devices,or the building structure must be modified extensively after completionin order to accommodate such lift devices.

As a result, various devices have been developed in the past fornegotiating stairways and the like. Some of these devices arepermanently installed along or on stairways to travel up and down thestairway. Often, these permanently installed machines also requiredmodification of the building structure for their installation. Stillother portable devices have been developed as well. Most, if not all,such devices require that the stairs have a constant pitch or slope inorder for the device to function. If the stairs have a different pitchor slope between landings or between stories, most such devices areincapable of proceeding beyond the first flight of stairs.

Thus, a stair-climbing apparatus solving the aforementioned problems isdesired.

SUMMARY OF THE INVENTION

The stair-climbing apparatus includes a wheeled undercarriage having aplatform and three sets of vertically adjustable wheel pairs extendingbelow the platform. Two of the three sets are also horizontallyadjustable beneath the platform. The apparatus uses conventionalelectrical power to drive the wheels in order to advance the device toand onto the stairs. The various wheel pairs adjust vertically so thatthe platform remains horizontal at all times, the wheel pairs adjustingsequentially as required to negotiate the stairs. While the leadingwheel pair or assembly is fixed at the forward end of the apparatus,i.e., it has no horizontal adjustment relative to the platform, theother two wheel pairs adjust forward and rearward beneath the platformin order to adjust for the difference in height between individual stepsand to adjust for different pitches or slopes of stairways. Thehorizontal and vertical adjustment of the wheel pairs beneath theplatform is controlled by proximity sensors, which detect the risers ofthe stair treads and adjust the wheel pairs accordingly. The proximitysensors may be of any conventional type, e.g., mechanical, infrared,ultrasonic, etc. A microcomputer or microcontroller receives theproximity signals and commands vertical and/or horizontal adjustment ofthe wheel pairs accordingly.

Vertical adjustment of the three sets of wheels is accomplished by apantograph mechanism for each wheel set. Horizontal adjustment of thesecond and third wheel sets is accomplished by a track mechanismextending along the length of the platform, each of the second and thirdwheel sets having its own independent drive for horizontal adjustment.The wheels are provided with conventional electric or other drive meansand brake means. The drive means may also serve as the brake means,depending upon the mechanism(s) incorporated.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a stair-climbing apparatus according tothe present invention, illustrating a first exemplary configuration.

FIG. 1B is a perspective view of the stair-climbing apparatus of FIG. 1,illustrating an alternative configuration.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, 2K, 2L, 2M, 2N, 2O, 2P,2Q, 2R, 2S, 2T, 2U, 2V, 2W, 2X, 2Y and 2Z are right side elevation viewsillustrating successive steps in the process involved as thestair-climbing apparatus of FIG. 1A ascends a flight of steps or stairs.

FIG. 3 is a block diagram of an exemplary control circuit for astair-climbing apparatus according to the present invention

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The stair-climbing apparatus is a stand-alone machine, i.e., it has noattachment to the stairway structure upon which it operates, nor doesthe stairway structure require any modification(s) to accommodate theoperation of the stair-climbing device. The apparatus is capable ofnegotiating stairways having different slopes and pitches of risers andtreads, even along the same continuous stairway.

FIGS. 1A and 1B of the drawings provide perspective views of thestair-climbing apparatus 10. FIG. 1A illustrates the apparatus 10 withall of its wheel trucks extended, and FIG. 1B shows the exemplaryretraction or raising of the first wheel truck and repositioning of thesecond end truck, as explained further below. The apparatus 10 comprisesa platform 12 having a series of wheel carriages and wheel trucksadjustably extending below the platform. The carriages and trucks arecontrolled by appropriate conventional sensors and an on-boardcomputerized system to adjust their positions as required to negotiate aflight of stairs.

The platform 12 has a first end 14, i.e., which is the leading end ofthe apparatus 10 when negotiating a flight of stairs, a medial portion16, and an opposite second or trailing end portion 18. The platform 12has a width 20 that is preferably somewhat narrower than a conventionalstairway. A plurality of wheel carriages is installed directly beneaththe platform 12. While any practicable number of such carriages may beprovided, the three carriages 22 a, 22 b, and 22 c of the exemplarystair-climbing apparatus 10 is considered to be optimum. However, itwill be seen that additional carriages (and their wheel truckassemblies, discussed further below) may be provided by using the samemechanism as provided for the three carriages illustrated and describedherein.

The first end wheel carriage 22 a is immovably affixed beneath theplatform 12, i.e., the first end carriage does not translate or moverelative to the platform. However, the medial wheel carriage 22 b andthe second end portion wheel carriage 22 c translate horizontally andlongitudinally beneath the platform 12 when the apparatus 10 is inoperation, as described further below. The longitudinal positioning ofthe two wheel carriages 22 b and 22 c is by means of an elongate rack 24extending along the longitudinal axis of the platform 12 from a pointnear the first end 14 of the platform and a point on the second endportion 18 of the platform 12. The medial wheel carriage 22 b has amedial drive mechanism 26 b extending therefrom and engaging the rack24, and the second end portion wheel carriage 22 c has a substantiallyidentical second end portion drive mechanism 26 c engaging the rack 24.The drive mechanisms 26 b and 26 c may comprise electric motors affixedto extensions of the respective carriages, each motor driving a pinionthat, in turn, engages a track extending along the rack 24. The rack 24may also include guide rails to hold the drive mechanisms 26 b, 26 c andtheir respective wheel carriages 22 b, 22 c in proper alignment as theyadjust longitudinally along the rack 24.

In FIG. 1A, it will be seen that the medial drive mechanism 26 b, andthus its medial wheel carriage 22 b, is positioned generally mediallyalong the rack 24, and the second end portion drive mechanism 26 c andits corresponding second end portion wheel carriage 22 c is positionednear the extreme second or rearward end of the rack 24 and platform 12.In FIG. 1B, the central or medial drive mechanism 26 b and its wheelcarriage 22 b are in the same positions as shown in FIG. 1A. However,the second end portion drive mechanism 26 c has been actuated to movetoward the opposite first end 14 of the platform 12, thus reducing thedistance between the second end portion drive mechanism 26 c and itscarriage 22 c and the medial drive mechanism 26 b and its carriage 22 b.The relative spacing between the wheel trucks and their wheels,discussed below, is adjusted accordingly.

Each of the wheel carriages 22 a, 22 b, and 22 c has a wheel truck 28 a,28 b, and 28 c, respectively, adjustably extending beneath thecorresponding carriage. The wheel trucks 28 a through 28 c aresubstantially identical to one another, each of the trucks 28 a, 28,b,and 28 c having a first end 30 and opposite second end 32 defining aspan 34 substantially equal to the width 20 of the platform 12. A firstwheel 36 extends from the first end 30 of each of the wheel trucks 28 athrough 28 c, and a second wheel 38 extends from the opposite second end32 of each truck. The wheels 36 and 38 are driven by conventional means,i.e., electric motors powered by an on-board electrical storage battery,the drive motors being contained in their respective wheel trucks or inthe hubs of the wheels. Such drive means is well known and conventional,and may be incorporated into the stair-climbing apparatus 10.

Each of the wheel trucks is adjusted vertically relative to the platform12 by a corresponding pantograph linkage 40 a, 40 b, and 40 c extendingbetween the wheel truck and its corresponding wheel carriage. The threepantograph linkages 40 a, 40 b, and 40 c are substantially identical toone another. Each linkage 40 a, 40 b, 40 c comprises a first arm 42 anda laterally opposite second arm 44, each of the arms 42, 44 having anupper or wheel carriage attachment end 46, 48 and an opposite lower orwheel truck attachment end 50, 52. The upper ends 46, 48 of the two arms42, 44 are pivotally attached to the corresponding lateral ends of theirrespective wheel carriages 22 a through 22 c, and the opposite lowerends 50, 52 of the arms 42, 44 translate laterally along thecorresponding wheel truck 28 a through 28 c.

Each wheel truck 28 a through 28 c has a first track 54 and a parallelsecond track 56 extending laterally across the truck. The lower end 50of the first arm 42 travels laterally along the first track 54, and thelower end 52 of the opposite second arm 44 travels laterally along thesecond track 56 in each wheel truck 28 a through 28 c. The lower ends50, 52 of the two arms 42, 44 travel in opposite directions to oneanother and towards the respective opposite ends 32 and 30 of each wheeltruck 28 a through 28 c as the wheel truck is lowered relative to theplatform 12. The lower ends 50, 52 of the two arms 42, 44 cross or passone another at the midpoints of their respective tracks 54 and 56, whenthe respective wheel truck has been raised somewhat from its fullyextended position, as shown with respect to the wheel carriage 22 a atthe lead end 14 of the apparatus 10 in FIG. 1B. The drive for thisarticulating arm system is accomplished by a motor 58 located on or ineach wheel truck 28 a through 28 c. The drive system may compriseconventional roller chains, toothed belts, worm drives, etc., asdesired.

FIG. 3 is a block diagram of an exemplary control circuit for thestair-climbing apparatus 10. The stair-climbing apparatus 10 includesproximity sensors 80 to sense when the apparatus approaches stairtreads. The proximity sensors 80 also may also have the capability tosense the height of the stair risers, or the height sensors may bediscrete devices that are generically included within the term“proximity sensors” in the present application. Such sensors are wellknown in the field of robotics. The apparatus 10 includes a controlcircuit 70 having a microcontroller 75 or microprocessor programmed toreceive signals from the proximity sensors 80 and raise or lower thewheel trucks 28 a, 28 b, and 28 c or drive the wheels forward by controlsignals to the motors 58, and to move the wheel carriages 22 b and 22 ctranslationally forward and rearward by control signals to the drivemechanisms 26 b and 26 c. Again, such control circuits 70 are well ownin the robotics art and need not be described further.

FIGS. 2A through 2Z are schematic side elevation views showing aprogression of operations of the apparatus 10 as it negotiates a flightof steps or stairs. In FIG. 2A, the apparatus 10 is shown in itscompletely collapsed configuration, i.e., all of the support arms of thepantograph assemblies or linkages 40 a, 40 b, and 40 c (shown in varyingstates of extension and retraction in FIGS. 2B through 2Z) have beenretracted to lower the platform 12 to its lowest state. The pantographassemblies 40 a, 40 b, and 40 c do not need to be fully collapsed as thedevice is still approaching the first step S1 of the stairway S, butcomplete retraction of all of the pantograph linkages provides morecompact storage and a lower center of gravity for the device.

The riser of the first step S1 is sensed by on-board detection means,e.g., infrared or other electromagnetic frequency means, ultrasonicdetection, mechanical sensors, etc. The stair-climbing apparatus 10includes means for detecting both horizontal proximity and the height ofthe risers of the stair steps. Such sensors are well known in the art,and need not be described further. As the first riser is sensed, theon-board computer or microcontroller system actuates the threepantograph linkage drive motors 58 of the three wheel trucks 28 a, 28 b,and 28 c, causing the linkages 40 a, 40 b, and 40 c to extend generallyas shown in FIG. 2B of the drawings.

It will be seen that the first wheel truck 28 a cannot remain retractedor partially extended to clear the height of the riser of the first stepS1, as the only support for the apparatus 10 would be by means of thetwo rearwardly located wheel trucks 28 b and 28 c, which would cause thedevice to tip forward. Accordingly, the second wheel truck 28 b istranslated forward by moving its wheel carriage 22 b forward along therack 24. The resulting configuration is generally as shown in FIG. 2C.

Once this has been accomplished, the first or forward wheel truck 28 amay be raised to clear the riser of the first step S1, generally asshown in FIG. 2D. The apparatus 10 then senses that the forward truck 28a is no longer blocked by close proximity of the riser of the first stepS1, and actuates the drive wheels 38 of the medial and/or second endwheel trucks 28 b and 28 c to move the apparatus 10 forward, therebyplacing the wheels 38 of the first wheel truck 28 a atop the tread ofthe first step S1, as shown in FIG. 2E.

At this point, the on-board sensor system senses the proximity of theriser of the first step S1 immediately in front of the second or medialwheel truck 28 b, and directs the medial pantograph linkage 40 b to liftthe medial wheel truck 28 b to the level of the first end wheel truck 28a to clear the riser of the first step S, generally as shown in FIG. 2F.Once this has been accomplished, the system applies motive power to thewheels of the first end and/or second end wheel trucks 28 a and 28 c(the wheels of the intermediate truck 28 b are not in contact with asurface at this point) to drive the apparatus 10 forward, therebyplacing the wheels of both the first end truck and medial truck 28 a and28 b atop the first step S1, generally as shown in FIG. 2G of thedrawings.

When this has been accomplished, the first end wheel truck 28 a is againlifted by actuating its pantograph mechanism 40 a in readiness forplacement of its wheels atop the second step S2, generally as shown inFIG. 2H. The apparatus 10 is once again driven forward, i.e., in thedirection of the rising stairway S, resulting in the wheels of the firstend truck 28 a resting atop the second step S2 and the wheels of themedial truck 28 b resting atop the first step S1 adjacent the secondstep riser, generally as shown in FIG. 2I of the drawings.

It will be noted that at this point there is sufficient horizontal roomfor the first wheel truck 28 a to advance until it reaches the riser ofthe third step S3. However, the medial wheel truck 28 b is abutting theriser of the second step S2, so no further forward progress may be madeuntil the medial wheel truck 28 b is lifted. This is shown in FIG. 2J ofthe drawings. Once this has been accomplished the apparatus 10 is oncemore driven forward until the wheels of both the first end wheel truck28 a and the medial wheel truck 28 b are resting atop the second stepS2, generally as shown in FIG. 2K.

This general process is repeated, as shown in FIGS. 2L and 2M, so thatthe first end wheel truck 28 a is raised in preparation for placementatop the third step S3 (FIG. 2L), and the apparatus is driven forward toplace the wheels of the first end wheel truck 28 a atop the third stepS3 while the medial wheel truck 28 b abuts the riser of the third stepS3. However, at this point it will be noted that the second end wheeltruck 28 c is abutting the riser of the first step S1. Thus, thestair-climbing apparatus 10 cannot advance further up the stairway S,regardless of the height of the medial wheels and wheel truck 28 b.Should the pitch or slope of the stairway S be somewhat different thanthat illustrated, the operating system of the apparatus 10 can adjustthe fore and aft position of the second end portion wheel carriage 22 c,and thus the fore and aft position of the second end portion wheel truck28 c as required.

When the above procedure has been carried out as necessary, the medialwheel truck 28 b is moved rearward by actuating its carriage drive 26 b(shown in FIGS. 1A and 1B), as shown in FIG. 2N of the drawings. Themedial pantograph linkage 40 b is then extended to lower its medialwheel truck 28 b, thereby once again placing the wheels of the medialtruck 28 b atop the first step S1 as shown in FIG. 2O of the drawings.

The rearward or second end support provided by repositioning the medialwheel truck 28 b adjacent the second end portion truck 28 c allows thesecond end truck 28 c to be lifted as shown in FIG. 2P. At this pointthe apparatus 10 is driven forward once again, positioning the secondend portion wheel truck 28 c and its wheels atop the first step S1immediately behind the medial wheel truck 28 b, generally as shown inFIG. 2Q of the drawings.

The process continues by lifting the medial wheel truck 28 b inpreparation for translating it forwardly, as shown in FIG. 2R. It willbe noted that due to the first end truck 28 a and the second end truck28 c being separated in height by only two steps, it is not necessary toextend the second end pantograph linkage 40 c to its full height. Thefirst end pantograph is completely retracted at this point, as is themedial pantograph. This raises the medial wheel truck 28 b and itswheels to the same elevation as the first or forward end wheel truck andwheels 28 a to allow the medial truck 28 b to move forward to rest uponthe third step S3 immediately behind the first end truck 28 a, asillustrated in FIG. 2S.

At this point, the apparatus 10 must lift the first end wheel truck 28 aonce again in preparation for placing it atop the fourth step S4.However, the pantograph linkages of the first end truck 28 a and themedial wheel truck 28 b are retracted to their maximum extent, i.e., thefirst end and medial trucks 28 a and 28 b are immediately adjacent theirrespective carriages 22 a and 22 b and cannot be raised further.Accordingly, all of the pantograph linkages 40 a, 40 b, and 40 c areextended to provide sufficient room for the subsequent retraction of thefirst end wheel truck 28 a, generally as shown in FIG. 2T, inpreparation for another move forward up the steps S. (It will be seenthat the control system may be programmed to hold the first or forwardend wheel truck 28 a in a completely retracted state rather thanextending it as shown in FIG. 2T, if so desired. The medial wheel truck28 b and second end portion wheel truck 28 c provide sufficient supportat this point.) In any event, the coordinated extension and retractionof the various pantograph linkages 40 a, 40 b, and 40 c as the apparatus10 negotiates the stairway S assures that the platform 12 always remainslevel throughout the entire operation.

Once the platform 12 has been lifted, as shown in FIG. 2T, the first orforward end wheel truck 28 a is lifted once again (if it was not held inits lifted state during the operation described above in the discussionof FIG. 2T) to clear the fourth step S4, as illustrated in FIG. 2U ofthe drawings. The proximity sensor system of the device determines thatthere is some distance between each of the wheel trucks 28 a, 28 b, and28 c and the corresponding risers of the steps S5, S4, and S2, andsignals the drive means to move the apparatus 10 forward to the positionshown in FIG. 2V of the drawings.

At this point, the medial wheel carriage 22 b is translated rearward,i.e., toward the second end portion carriage 22 c, to position it overthe second step S2 as shown in FIG. 2W. The medial wheel truck 28 b isthen lowered by extending its pantograph linkage 40 b to place thewheels 36 and 38 of the truck 28 b at rest on the second step S2, asshown in FIG. 2X. This allows the rearward or second end portion wheeltruck 28 c to be raised to clear the riser of the second step S2, asshown in FIG. 2Y. The horizontal clearance between the first and medialwheel trucks 28 a, 28 b and the risers of the respective steps S5 and S3allow the stair-climbing apparatus 10 to advance toward those steps andto position the second end portion wheel truck 28 c on the second stepS2, as shown in FIG. 2Z.

It will be seen that the above-described process may continue up theflight of stairs S to the extent necessary to reach the top of the stairor some other point along the stairway, as desired. The process wouldcontinue with the medial wheel truck 28 a retracting and moving forwardas shown in FIGS. 2R and 2S, the platform 12 then being raised, as shownin FIG. 2T. The process would continue generally as shown in FIGS. 2Uthrough 2Z, repeating the operation illustrated in FIGS. 2R through 2Zas necessary until reaching the destination on the stairway S.

While the operation has been described above as being a series offinite, sequential steps, it will be seen that the control system may beprogrammed to actuate the various operations in a fairly rapid and fluidsequence, allowing the stair-climbing apparatus to move smoothly andreasonably rapidly up a flight of stairs. It should also be noted thatwhile only a description of the sequential moves involved in travelingup a flight of stairs has been provided herein, it is but a trivialmatter to reverse the operation to allow the apparatus to travel downsuch a flight of stairs.

It will be seen that while the present discussion is directed to the useof the device on a fixed, stationary stairway, the stair-climbingapparatus may also be adaptable for use on a moving escalator byappropriate programming of the control system to account for themovement of the escalator steps at the bottom and top of the escalator.Such operations will of course depend upon the capability of the deviceto make positional adjustments to the wheel trucks sufficiently rapidlyto accommodate the lifting action of the escalator steps at the bottomof the escalator, and the leveling of the steps at the top.

The stair-climbing apparatus 10 may be adapted to carry or liftvirtually any practicable article up (or down) a flight of stairs. Theplatform 12 may be equipped with cargo tiedowns to secure various piecesof equipment thereto, e.g., large, heavy, and/or bulky office equipmentsuch as console copiers, desks, and the like, or large appliances suchas refrigerators, air conditioning units, stoves, etc. In addition, itwill be seen that appropriate means for securing a wheelchair or thelike to the platform may be provided, allowing the physicallyhandicapped to reach different floors or levels in a building structurewhere no other means is available to them.

It is to be understood that the present invention is not limited to theembodiment described above, but encompasses any and all embodimentswithin the scope of the following claims.

We claim:
 1. A stair-climbing apparatus, comprising: a platform having a first end, a medial portion, and a second end portion opposite the first end; a first end wheel carriage immovably affixed beneath the first end of the platform; a vertically adjustable first end wheel truck extending from the first end wheel carriage; a medial wheel carriage disposed beneath the medial portion of the platform, the at least one medial wheel carriage being horizontally positionable along the medial portion of the platform; a vertically adjustable medial wheel truck extending from the medial wheel carriage; a second end portion wheel carriage disposed beneath the second end portion of the platform, the second end portion wheel carriage being horizontally positionable along the second end portion of the platform; and a vertically adjustable second end portion wheel truck extending from the second end portion wheel carriage.
 2. The stair-climbing apparatus according to claim 1, further including a pantograph linkage adjustably extending between each of the wheel carriages and the corresponding wheel truck.
 3. The stair-climbing apparatus according to claim 2, wherein: each pantograph linkage comprises a first arm and a second arm, each of the arms having an upper end and a lower end opposite the upper end, each of the upper ends being pivotally connected to the corresponding wheel carriage, each of the lower ends selectively translating laterally within the corresponding wheel truck.
 4. The stair-climbing apparatus according to claim 3, wherein each said wheel truck includes mutually parallel first and second tracks, the lower end of each said arm selectively traveling laterally in the corresponding one of the tracks.
 5. The stair-climbing apparatus according to claim 1, wherein: the platform has a width; each said wheel truck has a first end, a second end disposed laterally opposite the first end, and a span extending between the first and second ends, the span being substantially equal to the width of the platform; and each said wheel truck further comprises a first wheel extending from the first end and a second wheel extending from the second end.
 6. The stair-climbing apparatus according to claim 1, further including: an elongate rack extending between the first end of the platform and the second end portion of the platform; a medial drive mechanism extending from said medial wheel carriage, the medial drive mechanism being operably connected to the rack and selectively driving said medial wheel carriage beneath the rack; and a second end portion drive mechanism extending from the second end portion wheel carriage, the second end portion drive mechanism being operably connected to the rack and selectively driving the second end portion wheel carriage beneath the rack. 